In a case where a respiratory organ does not function normally due to a respiratory disease, a neuromuscular disease, or the like, oxygen is delivered to the nose or the mouth of a patient with use of a mask, a nasal cannula, or the like. For a patient in need of highly concentrated oxygen, a method in which a mask, a nasal cannula, or the like is used in combination of a reservoir bag is, for example, employed. For a patient in need of respiratory assistance, a method is, for example, employed in which a lung of the patient is forcibly inflated by (i) causing a mask to be in absolute contact with the nose or the mouth of the patient and (ii) carrying out positive pressure ventilation.
Such a mask or a nasal cannula is used for many hours in a state where the mask or the nasal cannula is in close or absolute contact with the mouth, the nose, or the mouth and the nose of a patient. This gives a feeling of discomfort to the patient wearing the mask or the nasal cannula. Such a feeling of discomfort is increased, as therapeutic intervention, such as (i) a method in which the mask or the nasal cannula is used in combination with a reservoir bag and (ii) a method in which positive pressure ventilation is carried out, is increased. Accordingly, oxygen delivering means, such as a mask and a nasal cannula, have been suggested which allow treatment to be efficiently provided to a patient whose respiratory organ does not function normally, while hardly giving a feeling of discomfort to the patient.
For example, Patent Literature 1 suggests the following respiratory mask in view of a conventional rigid mask shell which poorly fits the face of a person and, therefore, may cause leakage of a supplied gas or give a feeling of discomfort to the person. That is, Patent Literature 1 suggests a flexible respiratory mask including: a mask shell adapted to fit over a respiratory orifice on a portion of the face of a person, the mask shell being made of a flexible material such as a woven fabric or a non-woven fabric, the mask shell including an impermeable coating extending over at least a portion of the flexible material; a hose connector extending through the flexible material of the mask shell and fastened to the flexible material, the hose connector being a hose connector to which a gas supply hose is attached; and at least one attaching member for securing the mask shell over the portion of the face of the person. A flexible nature of the flexible material allows the respiratory mask to conform to the face of a person, regardless of the shape or the size of the face of the person. Furthermore, permeability of the flexible material allows (i) discharge of exhaled air, (ii) discharge of an excessively supplied gas and expired CO2, and (iii) moisture to pass through the mask shell.
A nostril cannula is oxygen delivering means which is simple and less burdensome to a patient. However, the nostril cannula has a problem that, in a case where the nostril cannula is used outdoors, oxygen supply efficiency is decreased due to, for example, wind. In order to solve the problem, Patent Literature 2 suggests a nostril cannula substantially having a mask shape. That is, Patent Literature 2 suggests an inhalation gas supply mask including: a partition wall having a domical shape, the partition wall being brought into contact with an outer peripheral surface of an external nose of a user so as to cover the external nose; an inhalation gas introducing port via which a gas for inhalation is introduced inside the partition wall; and inhalation gas introducing means for introducing, via the inhalation gas introducing port, the gas to a space formed between (i) the wings and the tip of the nose of the user and (ii) the partition wall.
Patent Literature 3 suggests a respiratory mask for intermittently supplying positive pressure air to a user in accordance with a respiration cycle of the user. That is, Patent Literature 3 suggests a therapeutic gas introducing respiratory mask including: a positive pressure air supply port via which positive pressure air is supplied from above the nose of the user in a longitudinal direction of the nose; an exhaled air exhaust port located below the nostrils of the user; and a therapeutic gas introducing port which is provided in a vicinity of the exhaled air exhaust port and via which a therapeutic gas is introduced toward the nostrils of the user. The therapeutic gas introducing respiratory mask allows stably concentrated oxygen to be delivered to a user, and allows the user to rebreathe less exhaled air.